Wooden slats are used in various forms of coverings for architectural openings such as Venetian blinds, vertical blinds and shutters. A typical Venetian wood blind is made from a plurality of intrinsic wooden slats that are horizontally suspended from ladder tapes. The ladder tapes are connected to tilt rods which enable one leg of the ladder tape to be drawn up relative to the other leg of the ladder tape causing the wood slats to tilt. When the plane of the slats is substantially parallel with the plane of the architectural opening, light does not transfer through the blind and the blind is considered closed. When the plane of the slats is perpendicular to the plane of the architectural openings, light transfers through the blind, between the slats, and the blind is considered open. The typical blind has a bottom rail. Lift cords are coupled to the bottom rail and then run through the slats or alternatively are routed through the ladder tapes along the outside edge of the slats into the headrail. The lift cords are used to raise or lower the slats of the blind. Lift cords are generally pinched in a cordlock to hold the cords in place.
Wooden slats are also used with vertical blind hardware. A vertical blind has a headrail which includes a plurality of carriers typically mounted on a tilt rod. The carriers are attached to hangers from which the vertical wood slats will hang. Rotation of the tilt rod by either a cord or wand causes tilting of the vertical wood slats and the carriers are laterally movable to horizontally stack the slats adjacent a side or sides of an architectural opening or evenly distribute them across the opening.
A typical slat may be made from wood or wood components with the wood typically being a premium grade basswood or poplar that has a minimum amount of sugar deposits, knots and other natural wood characteristics. Consumers desire consistency in the appearance of the wood blind slats. If there is a knot or mineral deposit on the slat, it is expected that this flaw will appear consistently over the surface of the blind. Because of the variability of natural products, this is a difficult problem to overcome.
Generally wood blind slats are painted with a white or off-white pigment that substantially covers the wood characteristic of the wood slat. The painting or staining process uses paints and stains dissolved in organic chemical solvents that result in emission of harmful volatile organic compounds (VOCs) into the air. VOC emissions must be controlled by elaborate and expensive emission control devices. The volatile organic solvents are either recovered or burned before entering the atmosphere.
A problem faced in the fabrication of prior art wood blinds is the sorting of the wood slat for comparable characteristics and color. Another problem is checking slat bow, warp and camber. Stability is an inherent problem in thin continuous pieces of wood such as those used for wood slats. This problem is exaggerated in long slats. Continued cutting of forests results in the use of smaller and younger trees for wood for the wood slats. This young, small wood has more defects, warping, and bowing. Changes in humidity and temperature also effect the stability of wood slats.
To solve the problem with inconsistencies in the grade of the wood and to allow for the use of less expensive materials, film wrap has been used to surround the wood slat. The film wrap comes in many patterns and colors. Suppliers use UV resistant inks and typically print a top coat over these inks. The use of a film wrap provides substantial control over the aesthetic look of the product. It also alleviates any randomness that is present in the wood grain.
In combination with film wraps, finger jointed or engineered wood can be used as further explained below. This type of wood uses several pieces of wood from either the same species or different species that are finger jointed together. Because of the joints, finger jointed wood cannot be used for stained wood blind slats. The finger joints and the variation in color between the jointed wood are obvious even when the slat is stained. This is not aesthetically acceptable. Finger jointed wood can be used for painted wood slats, but the use of this wood requires additional coats to cover the joints compared to the number of coats required for continuous wood pieces. Additional coats of paint cost more money.
The use of finger jointed wood solves several problems associated with film blind slats. However, to use fingerjointed wood, the wood substrate must be film wrapped to hide the fingerjoints. The main problem discovered with film wrapping a finger jointed wood substrate is that moisture will penetrate the film and be absorbed by the wood. Where similar woods are used in the finger jointed wood, this is not a problem. Where several species are used to make up a finger jointed slat, this can be a problem. Different woods will absorb different levels of moisture at different rates. This results in different rates of expansion and moisture content along the length of the slat, subsequently resulting in delamination of the film from the finger jointed wood.
Prior art film wrapped slats have had problems. In high humidity, the film will delaminate from the underlying wood slat substrate. The films are laminated to inexpensive wood slat substrate that has defects and experiences warping and bow, possibly even greater than a painted wood slat. In typical prior art film wrapped wood slats, moisture will penetrate into the wood causing expansion and contraction of the wood slat which will result in decomposing, delamination, warping, cracking or the like of the film.
Therefore, it is an object of this invention to create a film wrapped wood blind that is stable in heat and moisture, that will not delaminate, and that can use a wood slat substrate that is both stable and inexpensive.